All companies developing or manufacturing pharmaceutical drugs, require a robust photostability testing process to ensure product quality and regulatory compliance. Inadequate testing can result in costly delays and lost revenue. Photostability Guidelines Testing is carried out on a single batch of material selected. Under some circumstances these studies should be repeated if certain variations and changes are made to the product e.
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It stipulates the following: Cool white fluorescent lamps with an output similar to that stipulated in ISO UVA fluorescent lamps with a spectral distribution of nm to nm and a maximum energy emission of between nm and nm.
A significant proportion of the waves must be within the ranges of nm to nm and nm to nm. The samples should be exposed to visible light VIS for at least 1. The specifications listed above are well known. Less familiar, however, are the intricacies that need to be taken into account when implementing the ICH Q1B guideline in photostability chambers featuring ICH-compliant irradiation facilities. This blog article introduces two light photometry methods for photostability tests that comply with ICH Q1B, discusses ICH-compliant light sources, and considers the key pros and cons.
Which light sensors are better: planar or spherical? There are two major differences between them — in one case, the sensor calculates the intensity of the radiation, whereas the other measures the actual radiation intensity.
In order to compensate for this reduction, planar sensors with diffusers use what is known as cosine correction. For all other angles of incidence see Figure 1 , the radiation intensity is calculated using a mathematical equation. This is why BINDER does not recommend using planar sensors with diffusers to test the photostability of new active substances and medicinal products. The same applies to planar sensors without diffusers, as they record even less of the actual radiation intensity.
As a result, the planar sensor needs cosine correction. The second difference relates to the hemispheres of measurement. As Figure 1 shows, a planar sensor can only observe radiation above the sensor surface.
In addition, it cannot record any radiation from below. Two spherical sensors that can be freely positioned Figure 3 control the light dosage of UVA at least watt hours per square meter and visible light at least 1.
Once the light dosage is achieved, the chamber switches off automatically. Figure 2: A spherical sensor makes it possible to measure the radiation intensity from all directions.
As the spherical sensor is the only sensor type that actually measures radiation intensity and records scattered radiation, we have been using exclusively spherical, freely positionable sensors in our KBF LQC photostability chambers for years now. BINDER does not advise using permanently installed sensors, as it can be difficult to fit samples and batches around them.
ICH-compliant light sources The VIS element is generated using bright white T8 fluorescent tubes in a rod shape with a diameter of 26 mm.
The emission range is between nm and nm. The relative spectral distribution conforms to the F6 standard cool white in accordance with ISO Depending on the type of unit, the length is either mm or mm.
The UVA element is generated using T8 fluorescent tubes in a rod shape with a diameter of 26 mm. The emission ranges are between nm and nm and between nm and nm. Photostability chambers from BINDER do not use dimmable fluorescent tubes, as this generally leads to changes in the spectral distribution.
What technical solutions are currently available to ensure reliable continuous operation? Which factors should you pay particular attention to and what are the advantages and disadvantages? Here are the 6 most important points to watch out for!
ICH Guideline Q1 to Q14
References 1. This document is an annex to the parent guideline and addresses the recommendations for photostability testing. Preamble The intrinsic photostability characteristics of new drug substances and products should be evaluated to demonstrate that, as appropriate, light exposure does not result in unacceptable change. Normally, photostability testing is carried out on a single batch of material selected as described under "Selection of Batches" in the parent guideline.
Q1B: Stability Testing: Photostability Testing of New Drug Substances and Products
Photostability Testing Guidelines of New Drug Substances